1. Field of the Invention
The invention relates to a unit fuel injector (UFI) and to a pump-line-nozzle unit (PLNU) for an internal combustion engine, with a pump element, the pump element having a pump chamber, and with a magnet valve, the magnet valve having a valve member and an armature; the magnet valve opens or closes a hydraulic connection between the pump chamber and a low-pressure region of the unit fuel injector.
2. Description of the Prior Art
In connection with the invention, the following discussion will refer only to the unit fuel injector (UFI), although pump-line-nozzle units (PLNUs) are always intended as well. The most essential distinction between unit fuel injectors and pump-line-nozzle units is that a pump-line-nozzle unit has a short high-pressure line between the pump element and the injection nozzle. For the present invention, this distinction does not matter, and hence the invention applies equally for unit fuel injectors and pump-line-nozzle units.
A unit fuel injector is known for instance from German Patent Disclosure DE 198 37 333 A1. In this unit fuel injector, the valve and the armature of the magnet valve are connected to one another nonpositively by a compression spring. Because the valve member and the armature are coupled only nonpositively, the dynamic performance of the magnet valve is difficult to control, and it is hardly avoidable that during operation, the armature and the valve member will repeatedly briefly separate from one another and after that collide again. This process is known as “bouncing”. The bouncing is unwanted, since it has an adverse effect on the precision with which the magnet valve opens and closes. Moreover, the bouncing causes high wear to the armature, which is of a soft material, so that the valve stroke and thus also the operating performance of the magnet valve vary over the course of time. Finally, it should also be mentioned that the armature must be guided in a capsule, and for structural reasons this guide can only be relatively short. As a consequence, the armature has a tendency to tilting, and the armature guide wears down relatively quickly.
In a unit fuel injector and a pump-line-nozzle unit according to the invention for an internal combustion engine, with a pump element, the pump element having a pump chamber, and with a magnet valve, the magnet valve having a valve member and an armature, and in which the magnet valve opens or closes a hydraulic connection between the pump chamber and a low-pressure region, it is provided that the armature is fixedly connected to the valve member.